Metal film deposition equipment

Abstract

To provide a metal film deposition apparatus that suppresses the occurrence of appearance defects in a metal film and improves the film deposition quality.SOLUTION: A film deposition apparatus 1A includes an anode 11, a solid electrolyte membrane 13 placed between the anode and a base material B, a power supply 14 which uses the base material as a cathode and applies voltage between the anode and the base material, a housing 15 which houses the anode and an electrolyte L containing metal ions and covers an opening 15a on the side of the base material with a solid electrolyte membrane, a liquid tank T which houses the electrolyte, a liquid supply pipe 50 through which the electrolyte flows from the liquid tank to the housing, a liquid discharge pipe 52 through which the electrolyte flows from the housing to the liquid tank, a supply device P which supplies the electrolyte from the liquid tank to the housing, and a gas-liquid separator 30 which is placed between the supply device and the housing in the liquid supply pipe and separates the gas contained in the electrolyte from the electrolyte.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a film forming apparatus for forming a metal film on a surface of a substrate. [Background technology]

[0002] Conventionally, a metal coating has been formed by depositing a metal on the surface of a substrate (for example, Patent Document 1). Patent Document 1 describes a metal coating forming device including an anode, a solid electrolyte membrane disposed between the anode and the substrate serving as the cathode, a power supply unit that applies a voltage between the anode and the substrate, and a liquid storage unit that stores an electrolytic solution containing metal ions between the anode and the solid electrolyte membrane.

[0003] In this film forming apparatus, the liquid storage unit is formed with a liquid supply port for supplying the electrolyte solution to the inside of the liquid storage unit and a liquid discharge port for discharging the electrolyte solution from the inside of the liquid storage unit. The film forming apparatus also includes a circulation mechanism for circulating the electrolyte solution within the liquid storage unit. This circulation mechanism supplies the electrolyte solution from the liquid supply port to the liquid storage unit and discharges the electrolyte solution used in the liquid storage unit during film formation from the liquid discharge port. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-169399 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when forming a metal film using the above-mentioned film forming apparatus, the electrolyte is circulated using a circulation mechanism, so there is a risk that gas such as air may be mixed into the electrolyte supplied to the liquid storage section. If the metal film is formed in a state in which gas is mixed into the electrolyte, the gas may locally obstruct the flow of current from the anode to the substrate. As a result, pits, pinholes, etc. may occur in the formed metal film, causing a defective appearance of the metal film.

[0006] The present invention has been made in consideration of the above-mentioned points, and its object is to provide a metal film forming apparatus that suppresses the occurrence of defective appearance of the metal film and improves the film forming quality. [Means for solving the problem]

[0007] In consideration of the above problems, a metal film forming apparatus according to the present invention includes an anode, a solid electrolyte membrane disposed between the anode and a substrate, a power supply unit that applies a voltage between the anode and the substrate using the substrate as a cathode, a container that contains the anode and an electrolytic solution containing metal ions and has an opening that opens to the substrate side covered with the solid electrolyte membrane, a liquid tank that contains the electrolytic solution, a liquid supply pipe that connects the liquid tank and the container and through which the electrolytic solution flows from the liquid tank to the container, and a liquid supply pipe that connects the liquid tank and the container and through which the electrolytic solution flows from the container to the liquid tank. a liquid discharge pipe through which an electrolytic solution flows, and a supply device provided in the liquid supply pipe for supplying the electrolytic solution from the liquid tank to the container, and a voltage is applied between the anode and the substrate with the solid electrolyte membrane in contact with the substrate, thereby reducing metal ions contained inside the solid electrolyte membrane to form a metal coating on the surface of the substrate, wherein the film formation device has a gas-liquid separator provided in the liquid supply pipe between the supply device and the container for separating gas contained in the electrolytic solution from the electrolytic solution.

[0008] According to the present invention, in the film forming apparatus, the electrolytic solution containing metal ions flows through a liquid supply pipe from the liquid tank to the container, and flows through a liquid discharge pipe from the container to the liquid tank. In the film forming apparatus, a voltage is applied between the anode and the substrate by the power supply unit while the solid electrolyte membrane is in contact with the substrate. As a result, the metal ions contained in the solid electrolyte membrane are reduced, and a metal film is formed on the surface of the substrate. The film forming apparatus has a gas-liquid separator that is provided between the supply device and the container in the liquid supply pipe and separates gas contained in the electrolytic solution from the electrolytic solution. Therefore, even if gas such as air present in the liquid supply pipe and the liquid discharge pipe is mixed into the electrolytic solution when the electrolytic solution flows between the liquid tank and the container, the gas (gas bubbles) contained in the electrolytic solution can be separated from the electrolytic solution before the electrolytic solution is supplied to the container. Therefore, it is possible to avoid the formation of a metal film in a state in which gas is mixed into the electrolytic solution, and therefore it is possible to avoid the occurrence of pits, pinholes, and the like in the formed metal film. Therefore, defects in the appearance of the metal coating are suppressed, and the quality of the formed coating can be improved.

[0009] In a preferred embodiment, the metal of the metal coating is a metal that becomes a divalent or higher metal ion, and the anode is a soluble anode made of the same metal as the metal coating. The gas-liquid separator has a gas outlet port that releases the gas separated from the electrolytic solution, and the gas outlet port is connected to the liquid tank so that the gas is supplied to the electrolytic solution contained in the liquid tank.

[0010] According to this aspect, monovalent metal ions may be introduced into the electrolyte in the container by dissolving the anode when forming the metal film, and the monovalent metal ions may be discharged into the liquid tank together with the electrolyte. Even in this case, gas containing oxygen gas is supplied to the electrolyte in the liquid tank through the gas outlet, so that the unstable monovalent metal ions can be oxidized to stable divalent or higher metal ions. As a result, since monovalent metal ions are chemically unstable and tend to precipitate in the liquid tank as sludge such as metal powder or oxide, the formation of sludge such as metal oxide or metal powder caused by monovalent metal ions can be avoided by making the sludge into stable divalent or higher metal ions. According to this aspect, even if the metal ions contained in the electrolyte are consumed by forming the metal film, the metal ions can be replenished by dissolving the anode. Therefore, a homogeneous metal film can be formed while replenishing the electrolyte with metal ions by dissolving the anode.

[0011] In a preferred embodiment, the film forming apparatus includes a base that holds the substrate below the container so that the substrate faces the solid electrolyte membrane, a lifting device that raises and lowers at least one of the container and the base so that the solid electrolyte membrane and the substrate can be brought into contact with and separated from each other, a gas-liquid exchanger that returns the electrolytic solution contained in the container to the liquid tank and introduces air into the container, and a control device that controls the operation of the lifting device and the gas-liquid exchanger, wherein the control device controls the operation of the gas-liquid exchanger to replace the electrolytic solution inside the container with atmosphere, and then controls the operation of the lifting device to separate the solid electrolyte membrane from the substrate.

[0012] According to this embodiment, after the electrolyte in the container is replaced with atmospheric air, the solid electrolyte membrane is separated from the substrate. Therefore, when the container is separated from the base, the solid electrolyte membrane is not deformed due to the weight of the electrolyte. However, when the electrolyte in the container is replaced with atmospheric air, the electrolyte and the atmosphere may be mixed inside the container, and the electrolyte returned to the liquid tank may contain atmospheric air. In this way, even if the electrolyte in the liquid tank contains atmospheric air, the electrolyte from which the gas contained in the electrolyte (e.g., atmospheric air) has been separated is supplied to the container, so that the appearance defects of the metal film caused by air bubbles can be suppressed. Effect of the Invention

[0013] According to the present invention, the occurrence of defects in the appearance of the metal coating can be suppressed, and the quality of the formed coating can be improved. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view of a metal film forming apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the film forming apparatus shown in FIG. 1, showing a state in which an electrolyte solution has been injected. [Diagram 3] 2 is a flowchart illustrating control of the film forming apparatus shown in FIG. [Figure 4] FIG. 5 is a schematic cross-sectional view of a metal film forming apparatus according to a second embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view of the film forming apparatus shown in FIG. 4, showing a state in which an electrolyte solution has been injected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a metal film forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[0016] First Embodiment Fig. 1 is a schematic cross-sectional view of a metal film forming apparatus 1A according to a first embodiment of the present invention. Fig. 2 is a schematic cross-sectional view of the film forming apparatus 1A shown in Fig. 1, showing a state in which an electrolytic solution L has been poured.

[0017] 1 and 2, the film formation apparatus 1A includes an anode 11, a solid electrolyte membrane 13 disposed between the anode 11 and a substrate B, a power supply unit 14 that applies a voltage between the anode 11 and the substrate B, and a container 15 that contains the anode 11 and an electrolytic solution L containing metal ions and has an opening 15a covered by the solid electrolyte membrane 13. In addition, the film formation apparatus 1A may further include a base 20 on which the substrate B is placed, and a linear actuator (lifting device) 70, as necessary, as shown in FIG.

[0018] The film forming apparatus 1A is an apparatus that applies a voltage between the anode 11 and the substrate B with the solid electrolyte membrane 13 in contact with the substrate B, thereby reducing metal ions contained inside the solid electrolyte membrane 13 to form a metal film (not shown) on the surface B1 of the substrate B. Note that in this embodiment, for convenience of explanation, the positional relationship of the components of the film forming apparatus 1A is specified on the assumption that the solid electrolyte membrane 13 is placed below the anode 11, and the substrate B is further placed below that. However, as long as a metal film can be formed on the surface B1 of the substrate B, the positional relationship is not limited to this, and for example, the film forming apparatus 1A in FIG. 1 may be upside down.

[0019] The substrate B functions as a cathode. The material of the substrate B is not particularly limited as long as it functions as a cathode (i.e., a surface having electrical conductivity), and may be made of a metal material such as aluminum or iron, or may be a resin, ceramic, or the like having a surface coated with a metal layer such as copper, nickel, silver, or iron.

[0020] The base 20 holds the base material B below the container 15 so that the base material B faces the solid electrolyte membrane 13. The base 20 may be made of an insulating material. In this case, the base material B is directly connected to the negative electrode side conductor 14a extending inside the base 20, and is electrically connected to the negative electrode of the power supply unit 14 via the negative electrode side conductor 14a. The base 20 may also be made of a conductive material (e.g., a metal). In this case, the negative electrode of the power supply unit 14 is connected to the base 20 via the negative electrode side conductor 14a. As a result, the base material B is electrically connected to the negative electrode of the power supply unit 14 via the base 20 and the negative electrode side conductor 14a.

[0021] The anode 11 has a shape corresponding to the film formation region of the substrate B. The film formation region of the substrate B means the portion of the surface B1 of the substrate B facing the anode 11. The anode 11 is a non-porous (for example, non-porous) anode made of the same metal as the metal of the metal coating, and is a block-shaped or flat anode. Examples of the material of the anode 11 include copper, nickel, gold, silver, and iron. In this embodiment, the anode 11 is dissolved by applying a voltage using the power supply unit 14, but the anode 11 does not need to be dissolved if the film is formed using only the electrolyte solution L containing metal ions. The anode 11 may be porous, but is more preferably non-porous. By using the non-porous anode 11, the metal coating formed on the substrate B is less susceptible to the surface condition of the anode 11.

[0022] The anode 11 is attached to a container 15 made of, for example, an insulating material. In this case, the anode 11 is electrically connected to the positive electrode of the power supply unit 14 via the positive electrode side conductor 14b. Furthermore, as long as a metal film can be formed by applying a voltage between the anode 11 and the substrate B, at least a part of the container 15 may be made of a conductive material (for example, a metal), and in this case, the power supply unit 14 and the anode 11 may be electrically connected to each other via the container 15 and the positive electrode side conductor 14b.

[0023] As described above, the electrolyte L is a liquid containing the metal of the metal film to be formed in an ion state, and examples of the metal include copper, nickel, gold, silver, and iron. The electrolyte L is an aqueous solution in which these metals are dissolved (ionized) with an acid such as nitric acid, phosphoric acid, succinic acid, nickel sulfate, or pyrophosphoric acid. For example, when the metal is nickel, the electrolyte L may be an aqueous solution of nickel nitrate, nickel phosphate, nickel succinate, nickel sulfate, or nickel pyrophosphate. Furthermore, when the metal is copper, the electrolyte L may be an aqueous solution containing copper sulfate, copper pyrophosphate, or the like.

[0024] The solid electrolyte membrane 13 is a flexible membrane that can be impregnated (contained) with metal ions by contacting with the above-mentioned electrolytic solution L. The solid electrolyte membrane 13 is not particularly limited as long as the metal ions can be reduced in the base material B when a voltage is applied by the power supply unit 14, and a metal derived from the metal ions can be precipitated. Examples of the material of the solid electrolyte membrane 13 include fluorine-based resins such as Nafion (registered trademark) manufactured by DuPont, hydrocarbon-based resins, polyamic acid resins, and resins having an ion exchange function such as Selemion (CMV, CMD, CMF series) manufactured by Asahi Glass Co., Ltd. As shown in FIG. 1 and FIG. 2, the solid electrolyte membrane 13 has an opposing surface 13a that faces the surface B1 of the base material B when attached to the container 15.

[0025] As shown in FIG. 1, the anode 11 and the solid electrolyte membrane 13 are attached to the container 15, and the container 15, the anode 11, and the solid electrolyte membrane 13 form a container space 15d for containing the electrolytic solution L. The anode 11 is attached to the inner surface of the container 15, which is disposed so as to surround the periphery of the anode 11. The container 15 also has an opening 15a that opens toward the substrate B side. The opening 15a opens downward, and the solid electrolyte membrane 13 is attached to the container 15 via, for example, a seal material (not shown) so as to cover the opening 15a. The anode 11 and the solid electrolyte membrane 13 are disposed apart from each other and in a non-contact state, and the container space 15d between them is filled with the electrolytic solution L. In this way, the container 15 has a structure in which the electrolytic solution L contained in the container space 15d directly contacts the anode 11 and the solid electrolyte membrane 13. The container 15 is made of a material that is insoluble in the electrolytic solution L.

[0026] Furthermore, the container 15 is formed with a supply flow path 15b for supplying the electrolytic solution L to the storage space 15d and a discharge flow path 15c for discharging the electrolytic solution L from the storage space 15d. The supply flow path 15b and the discharge flow path 15c are holes communicating with the storage space 15d, and are formed on either side of the storage space 15d. The supply flow path 15b is fluidically connected to a liquid supply pipe 50 described later, and the discharge flow path 15c is fluidically connected to a liquid discharge pipe 52 described later. The film forming apparatus 1A may have a heating device (not shown) on the upstream side of the supply flow path 15b (for example, in a liquid tank T that stores the electrolytic solution L), and the electrolytic solution L heated by this heating device may be supplied to the storage space 15d via the liquid supply pipe 50 and the supply flow path 15b.

[0027] The linear actuator 70 of the film forming apparatus 1A raises and lowers at least one of the container 15 and the base 20 so that the solid electrolyte membrane 13 and the substrate B can be brought into contact with and separated from each other. In this embodiment, the case where the base 20 is fixed and the container 15 is raised and lowered by the linear actuator 70 will be described. As shown in FIG. 1 and FIG. 2, the linear actuator 70 is provided on the upper part of the container 15. The linear actuator 70 is an electric actuator, and includes, for example, a guide 71 to which a motor (not shown) is attached, and a rod 72 that moves linearly relative to the guide 71. The rod 72 converts the rotational motion of the motor into linear motion, for example, by a ball screw or the like (not shown). The linear actuator 70 raises and lowers the container 15 relative to the base 20, making it possible to bring the solid electrolyte membrane 13 into contact with and separate from the substrate B. The linear actuator 70 may be provided on the lower part of the base 20. In this case, the base 20 can be raised and lowered to move the solid electrolyte membrane 13 toward and away from the substrate B. In addition, a device for raising and lowering the container 15 may be a hydraulic or pneumatic cylinder or the like.

[0028] The film forming apparatus 1A further includes a liquid tank T, a liquid supply pipe 50, a liquid discharge pipe 52, a pump (supply device) P, a gas-liquid separator 30, a gas-liquid exchange device 80, and a control device 90.

[0029] Next, a mechanism for circulating the electrolytic solution L in the film forming apparatus 1A will be described. As shown in Fig. 1, the electrolytic solution L is contained in a liquid tank T. A liquid supply pipe 50 connects the liquid tank T and the container 15. Specifically, one end of the liquid supply pipe 50 is fluidly connected to the liquid tank T in which the electrolytic solution L is stored, and the other end of the liquid supply pipe 50 is fluidly connected to a supply flow path 15b of the container 15.

[0030] In addition, the liquid supply pipe 50 is provided with a three-way valve 60. The three-way valve 60 switches the flow direction of the electrolyte L. Specifically, the three-way valve 60 switches the flow direction of the electrolyte L from the liquid tank T to the container 15 through the liquid supply pipe 50 and the flow direction of the electrolyte L from the container 15 to the liquid tank T through a liquid return pipe 56 described later. In addition, by closing the three-way valve 60, the flow of the electrolyte L from the liquid tank T to the container 15 through the liquid supply pipe 50 and the flow of the electrolyte L from the container 15 to the liquid tank T through the liquid return pipe 56 can be stopped. In other words, when the three-way valve 60 is switched so that the electrolyte L flows from the liquid tank T to the container 15, the electrolyte L flows from the liquid tank T to the container 15 through the inside of the liquid supply pipe 50. The liquid supply pipe 50 is provided with a pump P that supplies the electrolyte L from the liquid tank T to the container 15. Therefore, by rotating the pump P in the forward direction, the electrolyte L is sucked from the liquid tank T into the liquid supply pipe 50, and the electrolyte L is pumped into the accommodation space 15d of the accommodation body 15 via the gas-liquid separator 30 and the three-way valve 60 described below. The pump P is configured to be capable of rotating in the forward direction and the reverse direction. When the pump P rotates in the forward direction, as described above, the electrolyte L is supplied from the liquid tank T to the accommodation body 15. On the other hand, when the pump P rotates in the reverse direction, the electrolyte L is supplied from the accommodation body 15 to the liquid tank T through the liquid return pipe 56, as described in detail below.

[0031] As shown in FIG. 1, the gas-liquid separator 30 of the film forming apparatus 1A is provided between the pump P and the container 15 in the liquid supply pipe 50, and separates gas (gas bubbles) contained in the electrolytic solution L from the electrolytic solution L. The gas-liquid separator 30 includes a liquid outlet 32 ​​for discharging a liquid phase component, and a gas outlet 34 for discharging a gas phase component. The electrolytic solution L from which the gas has been separated by the gas-liquid separator 30 is introduced into the container 15 via the liquid outlet 32 ​​and the liquid supply pipe 50. The gas separated from the electrolytic solution L by the gas-liquid separator 30 may be discharged, for example, into the atmosphere via the gas outlet 34. The gas-liquid separator 30 may be, for example, one that operates by a surface tension method, or one that operates by a centrifugal force separation method using a swirling flow. The configuration of the gas-liquid separator 30 itself is known, so a detailed description thereof will be omitted.

[0032] 1, the liquid discharge pipe 52 connects the liquid tank T and the container 15. Specifically, one end of the liquid discharge pipe 52 is fluidly connected to the discharge flow path 15c of the container 15, and the other end of the liquid discharge pipe 52 is fluidly connected to the liquid tank T. The electrolyte L flows through the inside of the liquid discharge pipe 52 from the container 15 to the liquid tank T.

[0033] A pressure regulating valve 58 is provided in the liquid discharge pipe 52, which prevents the pressure (liquid pressure) of the electrolyte L contained in the storage space 15d from exceeding a predetermined pressure. The pressure regulating valve 58 can seal the inside of the storage space 15d by closing the three-way valve 60, thereby maintaining the liquid pressure of the electrolyte L at or below the predetermined pressure. This circulation mechanism allows the electrolyte L, the metal ion concentration of which has been adjusted to a predetermined concentration, to be supplied from the supply flow path 15b to the storage space 15d, and allows the electrolyte L used in the storage space 15d during film formation to be returned to the liquid tank T via the discharge flow path 15c.

[0034] A relief valve 62 is interposed between the container 15 and the pressure regulating valve 58 in the liquid discharge pipe 52. The relief valve 62 is opened, for example, when the inside of the liquid discharge pipe 52 becomes negative pressure (pressure lower than atmospheric pressure), and introduces the outside atmosphere into the container space 15d of the container 15. This relief valve 62 will be described later.

[0035] The gas-liquid exchanger 80 returns the electrolytic solution L contained in the container 15 to the liquid tank T, and also introduces air into the container 15. The gas-liquid exchanger 80 returns the electrolytic solution L from the container 15 to the liquid tank T through the liquid return pipe 56. One end of the liquid return pipe 56 is fluidly connected to the supply flow path 15b of the container 15, and the other end of the liquid return pipe 56 is fluidly connected to the liquid tank T. In this embodiment, a part of the liquid return pipe 56 is shared with a part of the liquid supply pipe 50. The liquid return pipe 56 may be a pipe separate from the liquid supply pipe 50.

[0036] The gas-liquid exchanger 80 includes a pump P, a three-way valve 60, and a relief valve 62. In this embodiment, the case where the pump P is a component of the gas-liquid exchanger 80 will be described. When the three-way valve 60 is switched so that the electrolytic solution L flows from the container 15 to the liquid tank T, the pump P is rotated in reverse, so that the electrolytic solution L flows from the container 15 to the liquid tank T through the inside of the liquid return pipe 56. That is, the pump P rotates in reverse, so that the electrolytic solution L is sucked from the container space 15d of the container 15 into the liquid return pipe 56, and the electrolytic solution L is pumped to the liquid tank T. At this time, the pump P continues to rotate in reverse, so that the relief valve 62 is opened, and the atmosphere is introduced into the container space 15d of the container 15. In this way, the gas-liquid exchanger 80 replaces the electrolytic solution L contained in the container space 15d with the atmosphere by the reverse rotation of the pump P, the switching of the three-way valve 60, and the opening of the relief valve 62. In the present embodiment, an example of the gas-liquid exchanger 80 has been described. For example, the gas-liquid exchanger 80 may be one that pumps compressed air from the supply flow path 15b of the container 15 to return the electrolytic solution L contained in the storage space 15d to the liquid tank T through the liquid discharge pipe 52. In this case, the compressed air remains in the storage space 15d, completing the exchange of the electrolytic solution L with the atmosphere.

[0037] The control device 90 controls the operation of the linear actuator 70 and the gas-liquid exchange device 80 (i.e., the pump P and the three-way valve 60). The film forming apparatus 1A may include a first pressure sensor 92 provided in the liquid discharge pipe 52, a second pressure sensor 93 provided in the liquid return pipe 56, and a stroke sensor (not shown) provided in the linear actuator 70. The first pressure sensor 92 detects the internal pressure of the liquid discharge pipe 52 and transmits the detected pressure signal to the control device 90 via a first pressure signal line 95. The second pressure sensor 93 detects the internal pressure of the liquid return pipe 56 and transmits the detected pressure signal to the control device 90 via a second pressure signal line 96. The stroke sensor (not shown) detects the stroke amount of the rod 72 relative to the guide 71 and transmits the detected stroke signal to the control device 90 via a stroke signal line 94. Note that the signals input to the control device 90 are only examples, and in addition to the above-mentioned signals, signals related to the rotation speed and rotation direction of the pump P may be input.

[0038] The control device 90 receives the above-mentioned signals and controls the operations of the components of the film forming apparatus 1A (for example, the pump P, the power supply unit 14, the three-way valve 60, and the linear actuator 70). Control of the film forming apparatus 1A using the control device 90 will be described with reference to FIG.

[0039] The control device 90 controls a conveying device (not shown) and the like, whereby the substrate B is placed on the base 20 (S100). At this time, the alignment of the substrate B with respect to the anode 11 attached to the container 15 may be adjusted, and the temperature of the substrate B may be adjusted. Next, a step of bringing the opposing surface 13a of the solid electrolyte membrane 13 into contact with the surface B1 of the substrate B is performed (see FIG. 2). In this step, the control device 90 transmits a drive signal to the linear actuator 70 via the stroke signal line 94 to extend the rod 72 (S110). As a result, the rod 72 moves downward relative to the guide 71, and the container 15 descends. Then, the solid electrolyte membrane 13 comes into contact with the substrate B from above. The control device 90 receives a stroke signal related to the stroke amount of the rod 72 from the linear actuator 70 via the stroke signal line 94. When the stroke signal reaches a predetermined value, the control device 90 determines that the solid electrolyte membrane 13 has come into contact with the substrate B, and stops the descent of the container 15.

[0040] Next, a step of storing the electrolytic solution L between the anode 11 and the solid electrolyte membrane 13 is performed (see FIG. 2). In this step, the control device 90 transmits a predetermined valve switching signal to the three-way valve 60 via the valve signal line 98 to switch the three-way valve 60 so that the electrolytic solution L flows from the liquid tank T to the container 15 through the liquid supply pipe 50 (S120). Next, the control device 90 transmits a predetermined drive signal to the pump P via the pump signal line 99 to rotate the pump P forward (S130). As a result, the electrolytic solution L sucked by the pump P from the liquid tank T is supplied to the container 15 via the gas-liquid separator 30 and the three-way valve 60.

[0041] Next, the control device 90 judges whether the pressure (liquid pressure) of the electrolyte L in the storage space 15d of the container 15 is equal to or higher than a predetermined pressure (S140). Specifically, the control device 90 receives the liquid pressure inside the liquid discharge pipe 52 via the first pressure signal line 95, and judges whether the liquid pressure is equal to or higher than a predetermined pressure. If the control device 90 judges that the liquid pressure is not equal to or higher than the predetermined pressure (NO in S140), the control device 90 controls the pump P to continue the forward rotation. On the other hand, if the control device 90 judges that the liquid pressure is equal to or higher than the predetermined pressure (YES in S140), the control device 90 transmits a drive stop signal to the pump P via the pump signal line 99 to stop the drive (S150). This stops the forward rotation of the pump P, and the supply of the electrolyte L from the liquid tank T to the container 15 is stopped. Next, the control device 90 transmits a signal to close the three-way valve 60 via the valve signal line 98 to the three-way valve 60 (S160). As a result, the inside of the accommodation space 15d is sealed by the pressure regulating valve 58 and the three-way valve 60, and the liquid pressure of the electrolyte L is maintained at or below a predetermined pressure.

[0042] In this manner, with the substrate B pressed by the solid electrolyte membrane 13 due to the liquid pressure of the electrolytic solution L, the control device 90 then executes a command to the power supply unit 14 via the voltage signal line 97 to apply a voltage between the anode 11 and the substrate B (S170). As a result, the metal ions contained in the solid electrolyte membrane 13 move to the surface of the substrate B in contact with the solid electrolyte membrane 13 and are reduced on the surface B1 of the substrate B. As a result, metal is precipitated on the surface B1 of the substrate B, and a metal film is formed on the surface B1 of the substrate B. At this time, since the electrolytic solution L is contained in the containing space 15d, the metal ions can be constantly supplied to the solid electrolyte membrane 13.

[0043] Next, the control device 90 uses a timer function built in the control device 90 to determine whether the elapsed time of the voltage application by the power supply unit 14 has passed a predetermined time (S180). If the control device 90 determines that the elapsed time of the voltage application has not passed the predetermined time (NO in S180), the control device 90 controls the power supply unit 14 to continue the voltage application. This is because it is determined that the thickness of the metal film on the surface B1 of the base material B is not sufficient. On the other hand, if the control device 90 determines that the elapsed time of the voltage application has passed the predetermined time (YES in S180), the control device 90 issues a command to the power supply unit 14 via the voltage signal line 97 to end the voltage application by the power supply unit 14 (S190). This is because it is determined that the thickness of the metal film on the surface B1 of the base material B is sufficient.

[0044] Next, the control device 90 controls the operation of the gas-liquid exchange device 80 to exchange the electrolyte L with the atmosphere inside the container 15 (S200, S210, S220), and then controls the operation of the linear actuator 70 to separate the solid electrolyte membrane 13 from the substrate B (S230). Specifically, the control device 90 transmits a predetermined valve switching signal to the three-way valve 60 via the valve signal line 98 to switch the three-way valve 60 so that the electrolyte L flows from the container 15 to the liquid tank T through the liquid return pipe 56 (S200). Next, the control device 90 transmits a predetermined drive signal to the pump P via the pump signal line 99 so that the pump P rotates in the reverse direction (S210). As a result, the electrolyte L sucked from the container 15 by the pump P is supplied to the liquid tank T via the three-way valve 60. At this time, as the pump P continues to rotate in the reverse direction, the pressure in the accommodation space 15d of the accommodation body 15 decreases (for example, becomes negative pressure), so that the relief valve 62 opens and the atmosphere is introduced into the accommodation space 15d of the accommodation body 15.

[0045] Next, the control device 90 judges whether the replacement in the accommodation space 15d of the accommodation body 15 (i.e., replacement from the electrolytic solution L to the atmosphere) is completed (S220). Specifically, the control device 90 receives the internal pressure of the liquid return pipe 56 via the second pressure signal line 96, and judges whether the internal pressure has become atmospheric pressure. If the control device 90 judges that the internal pressure is not atmospheric pressure (i.e., negative pressure) (NO in S220), the control device 90 controls the pump P to continue the reverse rotation. On the other hand, if the control device 90 judges that the internal pressure has become atmospheric pressure (YES in S220), the control device 90 transmits a drive signal to the linear actuator 70 via the stroke signal line 94 to return the rod 72 (S230). As a result, the rod 72 moves upward relative to the guide 71, and the accommodation body 15 rises. Then, the solid electrolyte membrane 13 is separated from the substrate B. When the stroke amount of the rod 72 received via the stroke signal line 94 reaches a predetermined value, the control device 90 determines that the solid electrolyte membrane 13 has been separated from the substrate B, and stops raising the container 15.

[0046] Finally, the control device 90 controls a transfer device (not shown) and the like to remove the substrate B from the base 20 (S240). In this manner, a series of controls of the film forming apparatus 1A using the control device 90 ends, and the control returns to the start.

[0047] Hereinafter, the operation and effects of the film forming apparatus 1A according to this embodiment will be described.

[0048] As described above, in the film forming apparatus 1A according to the present embodiment, the electrolytic solution L containing metal ions flows through the liquid supply pipe 50 from the liquid tank T to the container 15, and flows through the liquid discharge pipe 52 from the container 15 to the liquid tank T. The film forming apparatus 1A has a gas-liquid separator 30 that is provided between the pump P and the container 15 in the liquid supply pipe 50 and separates the gas contained in the electrolytic solution L from the electrolytic solution L. Therefore, even if gas such as air present in the liquid supply pipe 50 and the liquid discharge pipe 52 is mixed into the electrolytic solution L when the electrolytic solution L flows between the liquid tank T and the container 15, the gas (gas bubbles) can be separated from the electrolytic solution L before the electrolytic solution L is supplied to the container 15. Therefore, it is possible to avoid the formation of a metal film in a state in which gas is mixed into the electrolytic solution L, and therefore it is possible to avoid the occurrence of pits, pinholes, and the like in the formed metal film. Therefore, the appearance defect of the metal film is suppressed, and the film formation quality can be improved.

[0049] Moreover, the control device 90 separates the solid electrolyte membrane 13 from the substrate B after replacing the electrolyte L with atmospheric air inside the container 15. Therefore, when the container 15 is separated (e.g., raised) from the base 20, the solid electrolyte membrane 13 is not deformed due to the weight of the electrolyte L. Meanwhile, when replacing the electrolyte L inside the container 15 with atmospheric air, the electrolyte L and the atmosphere may be mixed inside the container 15, and the electrolyte L to be returned to the liquid tank T may contain atmospheric air. Thus, according to the film forming apparatus 1A according to the present embodiment, even if the electrolyte L in the liquid tank T contains atmospheric air, the electrolyte L from which the gas (e.g., the atmosphere) contained in the electrolyte L is separated is supplied to the container 15, so that the appearance defect of the metal film caused by the air bubbles can be suppressed.

[0050] <Second embodiment> FIG. 4 is a schematic cross-sectional view of a film forming apparatus 1B of a metal film according to a second embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of the film forming apparatus 1B shown in FIG. 4, showing a state in which an electrolytic solution is injected. The film forming apparatus 1B according to the second embodiment is different from the film forming apparatus 1A according to the first embodiment in that the gas outlet 34 of the gas-liquid separator 30 is connected to a different destination. The film forming apparatus 1B according to this embodiment is different from the film forming apparatus 1A according to the first embodiment in that the type of the anode 11 and the type of metal ions contained in the electrolytic solution L are limited. Hereinafter, the same reference numerals as those of the film forming apparatus 1A according to the first embodiment are used for configurations having the same or similar functions as those of the film forming apparatus 1A according to the first embodiment, and the description thereof is omitted, and the different parts are described.

[0051] As shown in FIGS. 4 and 5, the gas-liquid separator 30 has a gas discharge port 34 that discharges the gas separated from the electrolytic solution L. The gas discharge port 34 is connected to the liquid tank T so that the gas is supplied to the electrolytic solution L contained in the liquid tank T. Specifically, the gas discharge port 34 is connected to the liquid tank T via a gas supply pipe 54. One end of the gas supply pipe 54 is fluidly connected to the gas discharge port 34 of the gas-liquid separator 30, and the other end of the gas supply pipe 54 is fluidly connected to the liquid tank T. The gas separated from the electrolytic solution L flows from the gas discharge port 34 to the liquid tank T via the gas supply pipe 54.

[0052] The anode 11 of the film forming apparatus 1B according to this embodiment is a soluble anode made of the same metal as the metal film formed on the surface B1 of the substrate B. That is, the anode 11 is made of a material soluble in the electrolytic solution L. Examples of the material of the anode 11 include copper, nickel, zinc, and tin. For example, when the anode 11 is a soluble anode made of oxygen-free copper, monovalent copper ions may be introduced into the electrolytic solution L inside the container 15 by dissolving the anode 11. In addition, in the film forming apparatus 1B, the metal of the metal film formed on the surface B1 of the substrate B is a metal that becomes a divalent or higher metal ion. Examples of the metal include copper, nickel, tin, and zinc.

[0053] As described above, in the film forming apparatus 1B according to this embodiment, the metal of the metal coating formed on the surface B1 of the substrate B is a metal that becomes a divalent or higher metal ion, and the anode 11 is a soluble anode made of the same metal as the metal coating. In addition, the gas discharge port 34 of the gas-liquid separator 30 is fluidly connected to the liquid tank T via the gas supply pipe 54.

[0054] In the film forming apparatus 1B according to the present embodiment, for example, when the anode 11 is a soluble anode made of copper, monovalent copper ions may be introduced into the electrolyte L in the container 15 due to dissolution of the anode 11 during the formation of the metal film, and the monovalent copper ions may be discharged together with the electrolyte L into the liquid tank T. The monovalent copper ions may become copper hydroxide (Cu + +H2O→CuOH+H + ). Since copper hydroxide is chemically unstable, it is dehydrated to copper(I) oxide (2CuOH→ Cu 2 O +H2O) may precipitate in the liquid tank T. Also, the transfer of electrons between monovalent copper ions may cause the formation of divalent or higher metal ions (2Cu + →Cu+Cu 2+ ), the metal may aggregate to form metal powder and precipitate in the liquid tank T. However, according to the film forming apparatus 1B, a gas containing oxygen gas is supplied to the liquid tank T through the gas outlet 34 of the gas-liquid separator 30, so that the unstable monovalent copper ions can be oxidized to stable divalent or higher copper ions (2Cu + +1 / 2O2+2H + →2Cu 2+ +H2O). As a result, it is possible to avoid the generation of sludge such as metal oxide or metal powder caused by monovalent copper ions. This prevents the sludge from being mixed into the container 15, and allows a homogeneous metal film to be formed. Even if the copper ions contained in the electrolytic solution L are consumed by the formation of the metal film, the copper ions can be replenished to the electrolytic solution L by dissolving the anode 11. Therefore, it is possible to form a homogeneous metal film while replenishing the copper ions to the electrolytic solution L. EXAMPLES

[0055] The invention is illustrated by the following examples.

[0056] [Example 1] A glass epoxy board (FR-4) was prepared as a substrate for forming a film on its surface, which was made by impregnating a layer of glass fiber cloth with epoxy resin. Copper foil was formed on the surface of this glass epoxy board.

[0057] Next, a copper film was formed using the film-forming apparatus 1B according to the second embodiment shown in Fig. 4 and Fig. 5. A copper sulfate aqueous solution of "1M CuSO4 + 0.2M H2SO4" was used as the electrolyte, and a Cu plate was used as the anode. The film-forming conditions were as follows: the temperature of the electrolyte was 70°C, a solid electrolyte membrane (Nafion (manufactured by DuPont)) with a thickness of 8 µm was attached to the substrate, the liquid pressure of the electrolyte was 0.6 MPa, and the current density was 18 A / dm 2 , film forming area 100cm 2 The copper film was formed with a cumulative film formation time of 151 seconds. The gas-liquid separator used was a general one that operates by centrifugal force separation using a swirling flow.

[0058] [Example 2] A copper film was formed in the same manner as in Example 1. The difference from Example 1 was that phosphorus-containing copper was used for the anode, the temperature of the electrolyte was 42°C, and the current density was 7 A / dm 2 The film was formed using the film formation apparatus 1A according to the first embodiment shown in FIGS. 1 and 2 under film formation conditions with a cumulative film formation time of 388 seconds.

[0059] [Comparative Example 1] A copper film was formed in the same manner as in Example 1. The difference from Example 1 is that the copper film was formed using a film forming apparatus that did not have a gas-liquid separator.

[0060] <Checking the film formation status> The substrate on which the film was formed as described above was subjected to a film formation process with a film formation area (100 cm 2 The ratio of the visually defective area of ​​the metal coating to the total area of ​​the metal coating was measured. The visually defective area was calculated by measuring the area of ​​pits and pinholes formed in the metal coating. The results are shown in Table 1 (Example 1, Example 2, Comparative Example).

[0061] [Table 1]

[0062] (Results and Discussion) Here, when the ratio of the area of ​​the metal film with a defective appearance to the area of ​​the formed film is 10% or more, it is judged to be defective in appearance, and when it is less than 10%, it is judged to be good. The above 10% is used as a threshold value of the acceptable appearance state. As is clear from Table 1, in Examples 1 and 2, the ratio of the area of ​​the defective appearance is 0%, and pits and pinholes are not confirmed in the metal film. In Example 1, it is considered that the gas contained in the electrolyte is separated by the gas-liquid separator, and the electrolyte without the gas can be supplied to the container. In addition, it is considered that the monovalent copper ions generated when forming the metal film are discharged from the container to the liquid tank, but it is considered that the monovalent copper ions can be returned to divalent copper ions by supplying gas to the electrolyte in the liquid tank. This avoids the generation of sludge such as metal powder, and it is considered that the sludge can be prevented from being supplied to the container together with the electrolyte. In this way, it is considered that the generation of pits and pinholes in the metal film can be suppressed in Example 1. It is also believed that in Example 2, the gas contained in the electrolyte is separated by the gas-liquid separator, and the electrolyte that does not contain the gas is supplied to the container, and thus, it is believed that the generation of pits and pinholes in the metal film is suppressed in Example 2.

[0063] In contrast, in the comparative example, the proportion of the area with defective appearance was 25%, and pits and pinholes exceeding the threshold value were confirmed in the metal film. It is believed that the electrolyte in a gaseous state was supplied to the container in the comparative example. It is also believed that the monovalent copper ions generated during the formation of the metal film were discharged from the container to the liquid tank, but it is believed that the monovalent copper ions could not be returned to divalent copper ions, and sludge such as metal powder was supplied to the container together with the electrolyte. For this reason, it is believed that the area with defective appearance increased in the comparative example.

[0064] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the film forming apparatuses 1A and 1B according to the above-mentioned embodiments, and includes all aspects included in the concept of the present invention and the scope of the claims. In addition, each configuration may be appropriately and selectively combined to achieve the above-mentioned problems and effects. For example, the shape, material, arrangement, size, etc. of each component in the above-mentioned embodiments may be appropriately changed according to the specific aspects of the present invention.

[0065] For example, in the above embodiment, a case has been described in which the power supply unit 14 applies a voltage between the anode 11 and the substrate B in a state in which the circulation of the electrolytic solution L is stopped by closing the three-way valve 60 (see S150 to S190 in FIG. 3). However, when the power supply unit 14 applies a voltage, the three-way valve 60 does not have to be closed. In this case, the liquid pressure of the electrolytic solution L can be maintained at a predetermined pressure by continuing the forward rotation of the pump P. This makes it possible to separate gas contained in the electrolytic solution L whether before or during the formation of a metal film. [Explanation of symbols]

[0066] 1A, 1B: film forming device, 11: anode, 13: solid electrolyte membrane, 14: power supply unit, 15: container, 15a: opening, 20: base, 30: gas-liquid separator, 34: gas outlet, 50: liquid supply pipe, 52: liquid discharge pipe, 70: linear actuator (lifting device), 80: gas-liquid exchange device, 90: control device, B: substrate, B1: surface, L: electrolyte, P: pump (supply device), T: liquid tank

Claims

1. An anode; a solid electrolyte membrane disposed between the anode and a substrate; a power supply unit that applies a voltage between the anode and the substrate, the substrate being a cathode; a container that contains the anode and an electrolytic solution containing metal ions, and an opening that opens to the side of the base material is covered with the solid electrolyte membrane; A liquid tank that contains the electrolyte; a liquid supply pipe that connects the liquid tank and the container and through which the electrolyte flows from the liquid tank to the container; a liquid discharge pipe that connects the liquid tank and the container and through which the electrolyte flows from the container to the liquid tank; a supply device provided in the liquid supply pipe for supplying the electrolyte from the liquid tank to the container; a metal coating forming apparatus for forming a metal coating on a surface of the substrate by applying a voltage between the anode and the substrate in a state in which the solid electrolyte membrane is in contact with the substrate, and reducing metal ions contained in the solid electrolyte membrane, the film forming apparatus has a gas-liquid separator that is provided in the liquid supply pipe between the supply device and the container and separates a gas contained in the electrolytic solution from the electrolytic solution; The film forming apparatus includes: a base that holds the substrate below the container such that the substrate faces the solid electrolyte membrane; a lifting device that lifts and lowers at least one of the container and the base so that the solid electrolyte membrane and the base material can be brought into contact with and separated from each other; a gas-liquid exchanger that returns the electrolytic solution contained in the container to the liquid tank and introduces air into the container; A control device for controlling the operation of the lifting device and the gas-liquid exchange device, the control device controls the operation of the gas-liquid exchanger to replace the electrolyte solution inside the container with atmospheric air, and then controls the operation of the lifting device to separate the solid electrolyte film from the substrate.

2. The metal of the metal coating is a metal that can be a divalent or higher metal ion, the anode is a soluble anode made of the same metal as the metal coating, the gas-liquid separator has a gas outlet port that releases the gas separated from the electrolytic solution, 2. The metal film forming apparatus according to claim 1, wherein the gas release port is connected to the liquid tank so that the gas is supplied to the electrolytic solution contained in the liquid tank.

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